Many arrangements exist for presenting images in three-dimensions. One method is to color encode images for separate presentation to the left and right eyes of a viewer. The viewer perceives the motion picture as 3-D when viewing the projected images through special glasses having two different colored lenses which “decode” the separate right and left-eye images. This arrangement does not generate a true “auto-stereo” or automatic 3-D image in that, when viewed without the aid of the decoding glasses, the image does not appear three-dimensional.
Auto-stereoscopic displays require no viewing aids to be worn by the observer. Instead, the two views are only visible from defined regions of space. The region of space in which an image is visible across the whole of the display active area is termed a “viewing region”. If the observer is situated such that one eye is in one viewing region and the other eye is in the other viewing region, then a correct set of views is seen and a 3D image is perceived. For auto-stereoscopic displays of the “flat panel” type, the viewing regions are formed by a combination of the picture element (pixel) structure of the display and an optical element, generically termed a parallax optic. An example of such an optic is a parallax barrier. The parallax barrier permits the right eye of a viewer to view only the strips of the right-eye image and permits the left eye of a viewer to view only the strips of the left-eye image. Viewed separately, these left and right-eye images result in a single image which appears three-dimensional.
Generating an auto-stereo image requires the following. When passing through a specially computer-processed image, the light takes on the color of that specific area of the image. The colored light goes through each aperture of a parallax barrier screen, which in turn projects it toward one direction in space. The resulting images, as formed by all the apertures of a barrier screen, are specific to each point of view. By combining the plurality of points of view, the object will be perceived as a “real” 3-D illustration. As we increase the number of views and/or apertures the smoother the auto-stereo image becomes.
One problem with this arrangement comes from the fact that the large projection screen sits behind a parallax barrier. Indeed, the opaque regions of the parallax barrier block most of the light coming out of the projection screen and only those parts of the projection screen behind apertures are visible to the viewer. In this case, it is expensive and wasteful to light up the whole surface of the projection screen, since most of the light is never visible.
In the early 1900, Clarence W. Kanolt invented a static 3-D images system using a barrier-screen formed of continuous vertical lines (FIG. 1). From Kanolt's invention, a variety of applications are currently being developed, such as the 3-D television systems described in U.S. Pat. Nos. 2,209,747 and 5,663,831. To obtain a similar quality in the appreciation of the 3-D output, the process of using a pattern of regular continuous vertical lines requires that the definition be more than twice that of a process using staggered or offset slits. Therefore, given similar definition and/or limitations, the long continuous vertical lines will be more than twice as apparent thus negatively affecting the overall quality of the 3-D illustration since the observer is distracted by the continuous vertical lines.
Another form of barrier screen, which uses a staggered honeycomb pattern of small apertures, was developed to generate static 3-D photographic images, as described in U.S. Pat. No. 4,128,324. However, this technique minimizes image definition because each aperture can only provide a single pixel. Given similar ambient light, this system minimizes the quantity and brightness of light emanating from behind the image, which results in very poor visibility as defined by the distance of the observer from the illustration.
From continuous vertical lines, a new innovative system using a barrier screen formed of a parallax or short vertical slits or apertures, which are provided in an alternating grid pattern whereby the adjacent columns are staggered or offset from one another, was developed to generate a 3-D motion picture, as described in U.S. Pat. No. 6,128,132. It is desirable for the apertures to repeat or align in offset or alternate pattern of rows and for the pattern to be non-visually repetitive as it reduces the perceived pattern of dots or stripes. While this approach to the barrier screen attenuates the restrictions of the previous arrangements, the costs associated to the system found in U.S. Pat. No. 6,128,132 render it almost unfeasible.
The goal of U.S. Pat. No. 6,128,132 is to generate a 3-D motion picture using less than 100 views. Should this system be used to generate a similar fixed 3-D image, composed of 1,000 or more views, the cost would increase to such an extent as to render the making of this image cost-intensive and quite unfeasible.
Therefore, there is a need to develop a method and apparatus that will reduce the costs of generating a fixed 3-D image, while providing high quality and high-definition three-dimensional images.